Experimental Investigation on Shear Behavior of FRP Prestressed Concrete Beams with Shear Reinforcements

Abstract

To evaluate the shear behavior of prestressed concrete (PC) beams with fiber-reinforced polymer (FRP) reinforcements, a total of seven large-scale beams, including one without stirrups, one with steel stirrups, and the remaining five beams with glass FRP (GFRP) stirrups, were tested to failure. Each beam was longitudinally reinforced with posttensioned carbon FRP (CFRP) tendons and nonprestressed GFRP bars. The main test parameters included concrete compressive strength and shear span-to-effective depth ratio (a/d) which varied between 2.0 and 4.0. The shear crack width was measured by using digital image correlation technology. Two shear failure modes, including shear compression and diagonal compression, were observed in the tested beams. All beams exhibited significant reserve strength after the diagonal cracks were fully developed. The ratio of the ultimate shear capacity to the shear load at which the critical shear crack formed ranged from 1.32 to 1.55. The shear capacity of the FRP-PC beams increased with an increase in the concrete compressive strength or reduction in the a/d. It was found that an arching mechanism was developed in the FRP-PC beams with a/d of 3.0 of less. The stirrup strain limit of 0.005 specified in the Canadian recommendation proved to be reasonable for GFRP stirrups, while the stirrup strain limits in American guidelines appeared to be conservative. In addition, a database of shear tests on FRP-PC members was collected to assess the performance of shear strength provisions.